STOCKHOLM — Norwegian authorities say they are investigating a Norwegian citizen of Somali origin who is suspected of involvement in the terror attack on a mall in Kenya last month.

The PST security service said Thursday that it has received information suggesting the Norwegian “was involved in planning and carrying out the attack” that killed at least 67 people. It did not name the suspect.

The Somali Islamic group al-Shabab claimed responsibility for the assault and said it was in retaliation for Kenya’s sending of troops into neighboring Somalia.

PST said its agents were in Nairobi, working with Kenyan authorities investigating “to what degree” the Norwegian was involved and his links to al-Shabab. But the agency said the main goal of the investigation was to prevent any future attacks.